#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* names[] = { "book", "pen", "pencil", "eraser" };
int nb_products = 4;
int min_stock = 100;

// --------------------------------------------------
int compute_id(char* name) {

  int id = -1;
  int i;

  // Bug 1
  for ( i = 0; i <= nb_products; i++ ) {
    if ( strcmp(names[i],name) == 0 ) {
      id = i;
    }
  }

  return id;
           
}



// --------------------------------------------------
int read_one(FILE *ptr) {

  int max_length = 200;
  char name[max_length];
  float price;
  char available;
  int stock;
	  
  if (fscanf(ptr,"%s %f %c %d\n", name, &price, &available, &stock) < 4) {
    fprintf(stderr,"Error processing inventory file\n");
    exit(1);
  }

  int product_id = compute_id(name);
  if ( stock < min_stock ) {
    printf("Product id %d has low inventory (only %d items)\n", product_id, stock);
  } else {
    printf("Product id %d OK\n",product_id);
  }

  return stock;
 
}


// --------------------------------------------------
int bug(char *filename) {

  FILE *ptr;

  // Bug 3: total_stock should be initialized to zero
  int total_stock;

  if ( ( ptr = fopen(filename,"r")) ==  NULL ) {
    fprintf(stderr,"File %s could not be opened\n", filename);
    exit(1);
  }
  else {
    
    while (!feof(ptr)) {

      // Bug 2
      total_stock = read_one(ptr);

    }

  }
  fclose(ptr);
  
  return total_stock;

}


 

// --------------------------------------------------
void copy(char *input, char *output) {

  FILE *in;
  FILE *out;

  if ( ( in = fopen(input,"r")) ==  NULL ) {
    fprintf(stderr,"File %s could not be opened\n",input);
    exit(1);
  }

  if ( ( out = fopen(output,"w")) ==  NULL ) {
    fprintf(stderr,"File %s could not be opened\n",output);
    exit(1);
  }


  // As long as we didn't reach the end of the file
  while (!feof(in)) {

    int max_length = 200;
    char name[max_length];
    float price;
    char available;
    int stock;
	  
    if (fscanf(in,"%s %f %c %d\n", name, &price, &available, &stock) == 4) {
      fprintf(out,"%s \t %7.2f %c %d\n", name, price, available, stock);
    }

  }

  fclose(in);
  fclose(out);

}


// --------------------------------------------------
void read1(char *filename) {

  FILE *ptr;

  // Open a file for reading and check if operation succeeded
  if ( ( ptr = fopen(filename,"r")) ==  NULL ) {
    fprintf(stderr,"File %s could not be opened\n", filename);
    exit(1);
  }
  else {
    
    // As long as we didn't reach the end of the file
    while (!feof(ptr)) {
      
      int max_buffer = 200;
      char name[max_buffer];
      float price;
      char available;
      int stock;
	  
      // Approach 1: we know what to expect, so we can
      // read the correct types directly
      if ( fscanf(ptr,"%s %f %c %d\n", name, &price, &available, &stock) == 4 ) {
	printf("Method1: %s %f %c %d\n", name, price, available, stock);
      } 
    }
    
  }
  fclose(ptr);

}

// --------------------------------------------------
void read2(char *filename) {

  FILE *ptr;

  // Open a file for reading and check if operation succeeded
  if ( ( ptr = fopen(filename,"r")) ==  NULL ) {
    fprintf(stderr,"File %s could not be opened\n", filename);
    exit(1);
  }
  else {
    
    // As long as we didn't reach the end of the file
    while (!feof(ptr)) {
      
      // Approach 2: we can read whole line at once
      int max_buffer = 200;
      char line[max_buffer];

      if ( fgets(line, max_buffer, ptr) ) {

	// Getting rid of the newline character at the end of the string
	line[strlen(line)-1] = '\0';
	printf("Method2: %s\n",line);
      } 
      
    }
    
  }
  fclose(ptr);

}

// --------------------------------------------------
int main(int argc, char* argv[]) {


  if ( argc < 3 ) {
    fprintf(stderr,"Please enter old and new name of file to copy\n");
    return 1;
  }

  char *input_file = argv[1];
  char *output_file = argv[2];

  read1(input_file);
  printf("\n");
  read2(input_file);

  copy(input_file,output_file);

  // Uncomment to see the bugs
  //int stock = bug(input_file);
  //printf("The total number of items in inventory is %d\n",stock);

  return 0;
}